[@typescript-eslint/typedef] broken when used with a default parameter

[octogonz]

Repro

{
  "rules": {
    "@typescript-eslint/typedef": [
      "error",
      {
        "arrayDestructuring": false,
        "arrowParameter": true,
        "memberVariableDeclaration": true,
        "parameter": true,
        "objectDestructuring": false,
        "propertyDeclaration": true,
        "variableDeclaration": true
      },
    ],
  }
}

// error @typescript-eslint/typedef: expected a type annotation
function f(x: number = 1): void {
}

Expected Result

The error should not be reported because there is a type annotation: : number

Actual Result

The error is reported.

Versions

package	version
@typescript-eslint/eslint-plugin	2.0.0-alpha.4
@typescript-eslint/parser	1.13.0
TypeScript	3.5.3
ESLint	6.1.0

@JoshuaKGoldberg

[octogonz]

Here's a PR: #785